PHILADELPHIA — Most nights at 11:30, Sgt. First Class David Cassada is beyond tired. But in Phoenixville, Pa., 6,000 miles from Cassada's barracks in Iraq's Sunni Triangle, a 7-year-old boy is just home from school, racing to the computer.

So, tappity-tap, the National Guardsman logs on to the Internet game site and, together, father and son sail the high seas, pretending to be pirates.

Before Guard Capt. Michael Hood went to Iraq, he and his wife communicated online every day. Little has changed.

"It's almost like he's still here," said Amanda Goebel-Hood, of Ambler, Pa., who starts to check her in-box at noon.

At Al Asad Air Base in the country's western desert, National Guard Cpl. Derek Marinaro looks into a videoconference camera and signs to his deaf parents. Back in East Stroudsburg, Pa., the Marinaros scrutinize Derek's face and body language.

They seek the reassurance that others get from a voice on the phone, an answer to the question that haunts every military family: Is he really OK?

For U.S. troops and their loved ones, there has never been a war like Iraq.

Thanks to the Internet and a combat scenario that involves forays from a home base rather than advancement across enemy terrain, military personnel communicate with friends and family at home with unprecedented ease.

The result is near-daily chatter with the power to vanquish as well as create melancholy, say those on both sides of these intimate transactions.

Today's serviceman ought to be able to "spend as much time with his family as he'd like to," said John Harlow, founder of Freedom Calls Foundation, a nonprofit organization that provides free Internet, videoconferencing and phone service to military personnel in Iraq.

It's starting to happen. Although the letter remains sacred, it has been augmented with an array of possibilities.

With e-mail and instant messages, families send real-time encouragement to their men and women overseas. "I love you. I'm so proud of you."

And troops stay involved with their spouses. "Here's who to call about the furnace."

Calls are so cheap — from nothing at all to 21 cents a minute — that Cassada, 40, an electronics repair chief, talked his wife through setting up a new stereo system.

Videoconferencing allows military mothers to attend their children's birthday parties, and fathers to witness births.

Not long ago, National Guard Staff Sgt. Chad Nagel of Elizabethtown, Pa., joined some buddies and bought a webcam. "The invention of a lifetime," said Nagel, 32, who, like all of the military people in this story, was interviewed by e-mail from Iraq.

Now, the tank commander in Ar Ramadi blows kisses to his children at bedtime and admires their school projects.

Recent innovations are "incredible," said Morten G. Ender, a sociologist at the U.S. Military Academy at West Point, N.Y., who in 2004 surveyed 1,000 troops about methods they used at least twice a week to send word to friends and family.

About 15 percent said they used traditional mail. But a quarter of them called on the phone, and more than half e-mailed.

To young service personnel who were raised on the Internet, there's no contest between perfumed stationery and the instant gratification of the Web.

"Maybe a letter has more meaning than a screen," said Airman First Class Tarik Omar, 23, of Reading, Pa. But for him and his peers, he said, it's "the speed that counts."

In tents, trailers and buildings throughout Iraq, the military has set up more than 1,250 phones and 3,500 computer terminals. Phone usage is approximately 11.6 million minutes a month for 160,000 troops, the Department of Defense reports.

Michele Cassada, 38, holds her breath when she picks up the home phone and hears a delay. Is it a telemarketer, or the pause that announces an international call?

Cassada never leaves the house without her cell. "I don't even care about disturbing people," she said. "It's my husband. He's calling from Iraq."

About 2,000 troops a day pass through the three Iraqi facilities run by the Brooklyn, N.Y-based Freedom Calls, whose motto is "seeing is relieving." About 10,000 stateside businesses and other facilities have volunteered their teleconference equipment and conference rooms to the effort.

Some technologically savvy military personnel — especially those in the Guard, with skills from a variety of civilian occupations — purchase their own laptops, set up satellite dishes on the roofs of their quarters, and plug microphones into computers to make cheap international Internet phone calls.

Through e-mail and instant-messaging, troops seek a normalcy that only the mundane brings.

They answer questions about insurance agents and the whereabouts of the screwdriver set. And, some couples report, they argue — just like normal.

Marinaro used to call his sister, who would translate his words into sign language for his parents. The videoconference was a morale booster for him as well as them.

"Knowing that they are doing well makes my job over here that much easier," said Marinaro, 23.